Method for forming, opening and/or evaluating a connection site

ABSTRACT

System, apparatus and method for opening a heat-bonded connection formed between two hollow, flexible thermoplastic conduits. A pressure difference is created between the inside of at least one of the conduits and the ambient atmosphere sufficient to cause expansion of a wall of the tubing conduit in the vicinity of a frangible portion at least partially blocking the connection to disrupt the frangible portion and reduce the blocking.

The present disclosure generally relates to apparatus and methods foropening and/or testing or evaluating a connection between two flexiblethermoplastic conduits, such as, for example, fluid flow tubing in amedical fluid flow circuit employed in collecting, processing ortreating blood or blood components.

It is well known in the medical industry in general and particularly inthe blood banking field to use connection systems for connecting twoseparate tubing segments of a fluid flow set or circuit in a manner thatprevents the introduction of contaminants or preserves the sterility ofthe tubing, if pre-sterilized, during the connection process. Suchsystems have found application both in the large scale assembly ormanufacture of fluid flow circuits and in the hands of the ultimate userfor on-site assembly of fluid flow circuits having a desiredconfiguration. For example, a user may desire to carry out a particularmedical procedure, such as for collecting, processing or treating bloodand blood components. These devices or systems are commonly referred toin the medical field as sterile connection or sterile docking devices.

Known connection devices or systems include electron beam systems, as inU.S. Pat. No. 5,009,645; radiant energy systems that melt facingmembranes of fluid flow conduits, as in U.S. Pat. No. 4,157,723 andheated wafer systems that employ wafers for cutting and heat bonding orsplicing tubing segments together while the ends remain at a molten orsemi-molten elevated temperature, such as in U.S. Pat. Nos. 4,753,697,5,158,630 and 5,156,701.

More recently, a novel connection system and apparatus has beendescribed that connects flexible thermoplastic tubing segments by heator melt bonding the ends together while the ends are individuallyclamped into a closed position, preventing ambient contamination. Such asystem is described in detail in U.S. published patent application no.2013/0153048, which is incorporated by reference herein in its entirety.The connection made by such apparatus has a temporary closed conditionor crimped shape due to the high temperature and clamping of the endsduring connection. At the connection site, as a result of the connectionprocess, a portion of thermoplastic material such as a “skin”,“membrane” or “web” from the tubing, closes or reduces the cross sectionof the tubular portions or segments. This thermoplastic blocking portionof the connection can be broken or otherwise disrupted to open it bylight (in particular manual) external pressure or manipulation onto theconnection point or site.

The present apparatus and methods have particular application withrespect to the novel connection system described in the precedingparagraph. More particularly, the subject matter of this descriptionprovides a means and method to break or otherwise disrupt thethermoplastic portion and therefore more fully open such a connectionsite to allow or improve fluid flow between the conduits, withoutrequiring external manipulation. Optionally, the present apparatus andmethod also provides means and method for testing or evaluating theintegrity of a connection site after opening, although this aspect mayalso be used by itself, without the opening aspect, for testing suchconnections made using the above or other connection techniques.

Turning now to a more detailed description of the present subjectmatter, which is presented for purposes of description and notlimitation, various aspects and features of the present subject are seenin the attached drawings, of which:

FIGS. 1a-1c show, for background purposes, the device and method forforming a heat-bonded connection described in U.S. published patentapplication no. 2013/0153048, which is herein incorporated by referencein its entirety.

FIG. 2 is a diagrammatic sectional view of two flexible, hollow,thermoplastic conduits or tubing segments joined by a connection(illustrated by the darkened area) of the type resulting from theapparatus and method described in U.S. Pub. No. 2013\0153048.

FIG. 3 is a diagrammatic sectional view of two flexible, hollow,thermoplastic conduits or tubing segments as in FIG. 2, in combinationwith apparatus of the present disclosure, showing one conduit occludedon one side of the connection site, a pressure or force sensor betweenthe occlusion and the connection site and roller or peristaltic typepump in contact with the other conduit (on the other side of theconnection site).

FIG. 4 is a diagrammatic sectional view like FIG. 2 and illustrating thepump engaging and occluding the other conduit.

FIG. 5 is a diagrammatic sectional view like FIG. 2 and illustratingmovement of the pump roller toward the connection site to increaseinternal pressure in the other conduit.

FIG. 6 is a diagrammatic sectional view like FIG. 2 and illustrating theincrease in pressure in the other conduit causing disruption of theconnection site to open it for fluid flow between the conduits.

FIG. 7a is a diagrammatic sectional view like FIG. 2 and illustratingthe pump roller remaining in the position of FIG. 6 for a period of timefor the pressure/force sensor to sense the pressure in the respectiveconduit to evaluate the integrity of a connection site that, asillustrated, is intact and has no external leakage after opening.

FIG. 7b is a graph of pressure or force vs. time, illustrating apressure/force curve that would be sensed by the sensor exemplary of aconnection site free of leakage.

FIG. 8a is a diagrammatic sectional view like FIG. 7a and illustratingthe pump roller remaining in the position of FIG. 6 for a period of timefor the pressure/force sensor to sense the pressure in the respectiveconduit to evaluate the integrity of the connection site that, asillustrated, is not intact and has an external leak after opening.

FIG. 8b is a graph of pressure or force vs. time, illustrating apressure/force curve that would be sensed by the sensor exemplary of aconnection site with an external leakage.

FIG. 9 is a diagrammatic sectional view of the joined conduits of FIG.7a , after completion of integrity testing, with the pump roller nolonger compressing the respective conduit and the occlusion of theconduit on the other side of the connection site having been removed.

FIG. 10a is an elevational view depicting how the present subject mattermay be employed on particular apparatus for processing blood, bloodcomponents or other biological or other fluids.

FIG. 10b is an enlarged diagrammatic view of a portion of the apparatusof FIG. 10a showing apparatus of the present disclosure for openingand/or checking the integrity of a heat-bonded connection in adisposable fluid circuit employed with the apparatus.

FIGS. 11-13 are diagrammatic views of the portion shown in FIG. 10b ,illustrating opening of the connection site in a fluid circuit, similarto FIGS. 4-6.

FIGS. 14a and 14b are diagrammatic views of the portion shown in FIG.10b , illustrating an integrity check of a connection site that is freeof external leakage and the typical pressure/force vs. time graph thatwould reflect such connection site to the sensor.

FIGS. 15a and 15 b are diagrammatic views of the portion shown in FIG.10b , illustrating integrity check of a connection site that is notintact and is experiencing external leakage and the typicalpressure/force vs. time graph that would reflect such as connection siteto the sensor.

SUMMARY OF DISCLOSURE

The following is to provide a summary of various embodiments and/oraspects of the present subject matter and is not intended to includeevery embodiment or aspect or to provide a more detailed description,which may be found in the later detailed description.

In accordance with one aspect of the present subject matter, a method isprovided for opening a heat-bonded connection formed between two hollow,flexible, thermoplastic conduits, which connection includes a portion ofthermoplastic material at least partially blocking internalcommunication between the conduits. In one embodiment the methodincludes creating a pressure difference between the inside of at leastone of the conduits and the ambient atmosphere sufficient to causeexpansion of the conduit in the vicinity of the thermoplastic portion todisrupt the frangible portion and reduce the blocking. By reducing theblocking, it is not meant that the effect of the blocking is completelyremoved, but that the amount of blockage is reduced so that improvedflow (which may differ significantly in different applications) isprovided through the connection site.

In accordance with another embodiment, the pressure difference ordifferential optionally may be created when the thermoplastic materialat an elevated temperature, such as an elevated temperature that is theresult of heating that occurs during a heat bonding process. Theincreased pressure difference may also be created when the connectionsite is at ambient temperature, but for a given connection site andconduit material and thickness, less pressure difference may be requiredif the thermoplastic material is at an elevated temperature.

If the pressure differential is created while the connection site is atan elevated temperature, in one embodiment the pressure difference iscreated when the thermoplastic material has a temperature where it isstill relatively soft or at least not fully hardened, such as optionallyabove its glass transition temperature.

In accordance with another embodiment, the method of any of the aboveexamples may be provided in which the pressure difference is created byincreasing the pressure inside of the conduit above the ambientpressure.

In accordance with another embodiment, the method of any of abovemethods may be provided in which the pressure difference is created byreducing the pressure outside of the conduit below the pressure insidethe conduit. This may be used alone or in combination with increasingthe pressure within the conduit.

In another embodiment, any of the above methods may include occludingone or both of the thermoplastic conduits and increasing thepressure/force difference between the pressure inside the conduit(s) andthe ambient environment until the frangible portion is disrupted. Asexplained above, this may be done by increasing the internal pressure inone of the conduits, decreasing the external pressure, or both.

Where the present subject matter is employed in combination with orsequentially to formation of a heat bond between the two conduits, suchas that for example described in U.S. 2013/0153048, in accordance withanother aspect, which may be used with any of the embodiments discussedabove, the pressure difference may optionally be created, relativelysoon after formation of the heat-bonded connection. For example, almostimmediately after the connection is formed, the connection site can beopened with internal pressurization of one of the conduits to a pressureas low as about 200 mmHg (3.9 psi), but there is increased risk thatopening this quickly will result in loss of connection integrity becausethe plastic is still too soft or molten. Preferably, but notexclusively, the pressure to open the connection site is applied afterabout 5 seconds to allow greater cooling of the connection site, but notmore than about 10 seconds, as the pressure to open the connection siteincreases as the site cools. Allowing cooling for more than 10 secondsmay require the use of excessive pressure to open the connection site Atabout 5-10 seconds after formation, the connection site can typically beopened by internal pressurization of one of the conduits to about1000-1500 mmHg (19-29 psi). The pressures and times required may bevaried with enhanced cooling or supplemental heating of the connectionsite

In connection with a further aspect, any of the above embodiments mayinclude observing the pressure/force difference in one or both of theconduits to detect disruption of the blocking portion at the connectionsite, and/or after the blocking portion is disrupted to determine theintegrity of the heat-bonded connection site. In other words, theinternal pressure or pressure differential could be observation from theabout the time of disruption to detect whether the pressure/forcedifference remains relatively unchanged, reflecting that the connectionsite is intact, has integrity and is not leaking, or whether thepressure/force difference changes, i.e. reduces, suggesting the presenceof a leak and lack of connection integrity. The observation forintegrity could be done over a limited period of time. Large leaks wouldlikely be detected relatively quickly, such as within about 5 seconds,by degradation of internal testing pressure. Detection of very small“pin hole” size leaks may require observation for as long as about 20-30seconds. For safety purposes, the default observation time period orduration would be the longer time needed to better detect even smallleakages, although that time period could be cut short if a large leakis detected earlier. The result could of course be reflected in anaudible or visual signal, alarm or indication to a user so that, in theevent of leakage, corrective action could be taken where feasible or theconduits and any associated fluid circuits could be discarded.

The above aspect, i.e., the testing of connection integrity by sensingpressure/force difference over a period of time, could also be usedindependently of any opening feature or benefit to evaluate theintegrity of a heat bonded or other connection arrangement between twoconduits in order to test for integrity of the connection site.

In a further aspect of any of the embodiments of the present subjectmatter employing observation of the pressure/force difference, thepressure difference could be increased until the monitoring detectsdisruption of the thermoplastic portion at the connection site. Forexample, where the pressure/force difference is increased by increasingpressure within a particular conduit, the pressure/force in the otherconnected conduit may be observed, and disruption and opening of theconnection site evidenced by increase in pressure in the other connectedconduit. It is understood that the pressure/force difference, regardlessof how created, could have an upper limit, which is the burst pressureof the conduit. If disruption is not detected by the time thepressure/force difference nears the burst pressure or is within aselected safety margin, the pressure increase can be stopped and theuser alerted that manual manipulation to open the connection site orother action may be required. As explained earlier, the disruption ofthe thermoplastic portion blocking the connection site may optionally befollowed by monitoring of the pressure in the joined conduits such asfor a period of time to evaluate connection integrity.

In another embodiment of the present subject matter, connection openingapparatus is provided for opening a heat-bonded connection formedbetween two hollow, flexible, thermoplastic conduits, which connectionincludes a portion of thermoplastic material at least partially blockinginternal communication between the conduits. The apparatus comprises anoccluder, such as but not limited to a valve or clamp, cooperative withone of the thermoplastic conduits to block flow through the conduit, apump cooperative with the other of the other of the fluid conduits tocreate pressure within the other of the fluid conduits in proximity tosuch a connection and a pressure sensor cooperative with the onethermoplastic conduit and operable to sense pressure inside the oneconduit. In this arrangement, pressure from the pump is operable todisrupt the blocking portion to reduce the amount of blocking and thesensor is operable to sense pressure in the one conduit, for example, tosense a pressure increase in the one conduit in response to disruptionof the blocking portion.

In the apparatus of the above embodiment, the sensor may optionally beconfigured to sense pressure for a period of time after disruption ofthe blocking portion to assess connection integrity. As explainedbriefly earlier, the above apparatus also may be configured to provideonly a check of the integrity of a heat bonded conduit connection thatis formed by other types of apparatus or methods.

In connection with yet a further embodiment, a durable blood processingdevice is provided for processing blood in a disposable fluid circuit ofthe type including a blood separator and an associated fluid flow tubingcircuit. The durable processing device may comprise a station forreceiving a blood separator, at least one control valves for controllingflow through the fluid circuit, and apparatus for opening a heat-bondedconnection in the fluid circuit, which connection is formed between twoflexible, hollow, thermoplastic conduits, and includes a portion ofthermoplastic material at least partially blocking internalcommunication between the conduits. The opening apparatus includes avalve cooperative with one of the conduits to block flow therethrough, apump cooperative with the other of the conduits to create pressurewithin the other of the fluid conduits in proximity to such a connectionto disrupt the blocking portion and thereby reduce the amount ofblocking, and a pressure sensor cooperative with the one conduit andoperable to sense pressure inside the one conduit.

In another embodiment, the above durable blood processing device furtherincludes connection apparatus for forming a heat-bonded connectionbetween two thermoplastic conduits of a disposable fluid flow circuit,which connection includes a portion of thermoplastic material at leastpartially blocking internal communication between the conduits. Theconnection forming apparatus may be located on the durable processingdevice so as to form such connection between the valve and sensor on oneside of the connection and the pump on the other side of the connection.

In connection with another embodiment, a connection system is providedfor forming a heat-bonded connection between two hollow, flexible,thermoplastic conduits. The system includes connection forming apparatusand connection opening apparatus. The connection forming apparatusincludes at least two relatively pivotable or rotatable members, eachcooperative with a separate thermoplastic conduit so as to pivotally orrotatably move ends of the respective conduits between a spaced-apartposition and an end-to-end contacting position for forming a heat-bondedconnection therebetween. The connection opening apparatus includes avalve cooperative with one of the conduits to block flow therethrough; asensor cooperatively associated with the one of the conduits for sensingpressure inside of the one conduit between the connection and the valve,and a pump cooperative with the other of the conduits to increasepressure within the other of the conduits to disrupt and open theconnection.

DETAILED DESCRIPTION

Turning now to a more detailed description, the attached drawings areprovided for purposes of illustration and not limitation. As notedearlier, the present subject matter is particularly useful in openingand checking the connection site formed by heat connection devices suchas illustrated in U.S. published patent application no. 2013/0153048.FIGS. 1a-1c are taken from that application and illustrate, forbackground and description purposes, the prior device and method forforming a heat-bonded connection between two flexible thermoplasticconduits or tubings. Without unduly elaborating on the details of suchdevice and method, which are fully explained in the publishedapplication, sealed conduit or tubing segments 20 and 22 are eachreceived on a rotatable disc, respectively 24 and 26. Each disccooperates with two pair of clamping jaws 28 and 30, one of which mayalso be a high frequency voltage electrode for heating the clampedtubing. As seen in FIG. 1B, after the conduits or tubings are clampedand heated, the discs shift laterally to separate the clamping jaws androtate to the positions seen in FIG. 1B. This exerts a tensile and shearforce on the tubing segments, such that each tubing segment is separatedfrom the sealed end portion of that segment. Because the clamping jaws28 keep the ends of the segments clamped and sealed, sterility of thesegments, if pre-sterilized, is maintained and, in any event, the tubingsegments are safeguarded from introduction of ambient bacteria ormicroorganisms.

After the tubing ends are brought into a facing position, as shown inFIG. 1B, the discs move laterally again, bringing the conduit/tubingends into direct contact. Because this happens while the tubing ends arestill at elevated temperature and in semi-molten state, they form anintegral, welded bond or connection site 32. Because the process resultsin a thermoplastic portion or “skin” 38 blocking communication betweenthe lumen of the joined conduits or tubes, after cooling, manualmanipulation is employed to break the skin and open the connectionbetween the tubing segments for fluid flow. The present subject matter,as described below, avoids the need for manual manipulation andoptionally also automates testing of the connection site integrity.

FIGS. 2-9 are diagrammatic illustrations of method and apparatus of thepresent subject matter for opening and/or testing the integrity of aheat-bonded connection 32 (sometimes called a heat-weld or melt-bondconnection) joining two flexible, thermoplastic, conduits 20 and 22formed by the apparatus and method such as (but not limited to) thatdescribed above and disclosed in U.S. published application no.2013/0153048, which results in a portion of thermoplastic material thatat least partially blocks flow between the conduits.

Before turning to further details of the method and apparatus, it shouldbe noted that it is not required for the connection forming apparatus ofthe above published application or for the subject matter describedherein that the conduits to be of the same size or material, althoughthe material and size should be sufficiently compatible as necessary toform the heat-bonded connection. It is contemplated for application inmedical fluid flow circuits that the conduits 20 and 22 will typicallybe flexible tubing of polyvinyl chloride (“PVC”) or other flexiblethermoplastic material, with an interior lumen for flowing medicalfluids such as blood, blood components, anticoagulant, saline, or otherliquids. As used hereinafter, “medical fluids” is intended to have acomprehensive definition to include all of the above, and “blood” isintended to include whole blood and blood components such as plasma orconcentrated red cells, either with or without other blood components oradded liquids such as anticoagulant. In a typical fluid flow circuit forcollecting, processing or treating blood or blood components, such asthe type marketed by Fenwal Inc., of Lake Zurich, Ill., the conduits maybe hollow PVC tubing, a flexible thermoplastic material, having aninternal lumen diameter of about 0.118-0.126 inches (3-3.2 mm) and awall thickness of about 0.025-0.03 inches (0.635-0.762 mm). As notedabove, however, this subject matter is not limited to a particular sizeor material for the conduits.

Turning back now to FIG. 2, the thermoplastic portion 38 blocking theconnection site is also referred to as the “skin” or “web” or “portion”or “blockage.” It at least partially blocks communication between lumen34, 36 of the respective conduits 20, 22 and is exemplified by stippledarea 38, which is not intended to accurately show the dimensions of theblockage, which may vary. It is anticipated that most often, thethermoplastic portion 38 formed during the connection described abovewill completely block communication between the lumen 34, 36, althoughthat need not be the situation for the present method and apparatus tobe useful.

Turning to FIG. 3, which depicts one embodiment of apparatus of thepresent subject matter and one of the first steps in the present method.The apparatus includes an occluder 40, a pressure or force sensor 42 anda pump 44. These devices may be part of a larger fluid processing devicesuch as a blood collection and/or separation instrument, or may be partof a device devoted to making a heat-bonded connection between tubingsegments of a fluid flow circuit, for example a disposable bloodcollection or processing flow circuit. On whatever apparatus they areused, these devices may be relatively located or disposed so that thejoined conduits 20, 22 are positioned or positionable such that conduitscooperate with other respective devices disclosed herein. It may beparticularly beneficial, for example, if the occuluder, sensor and pumpare also located or used in association with apparatus for forming theheat bonded connection whereby the opening and/or integrity testingdescribed can be performed soon after the heat-bonded connection isformed and while the blocking portion 38 has not fully hardened, thuspotentially requiring less pressure differential to disrupt (such asbreak or deform) the blockage to open the connection site.

More specifically, the occluder can be any suitable device such as, forexample, an external clamp (manual or automatic) that can compress thetubing closed, a stopcock or other occlusion means. Alternatively, theoccluder could be an internal frangible closure member within conduit 20of the type well known in the blood banking industry. Use of an internalfrangible closure would normally require manipulation of the closure toallow flow through the conduit 20 after the opening of the blockage 38and/or the connection integrity sensing takes place.

The pressure or force sensor 42 is located along the conduit 20 betweenthe occluder 40 and the blockage 38 to monitor the pressure in theconduit 20 between the blockage and the occluder. This sensor may beused to detect opening of the blockage. It may also be used incombination with the opening of a blockage or, independently, to monitorthe pressure over a period of time to determine connection 32 integrityand specifically to identify whether there is leakage at the connectionsite.

The sensor 42 may be of any suitable construction or employ any suitabletechnology for monitoring the internal pressure of conduit 20. This maybe accomplished, for example, by monitoring the expansion of the conduitwall or the force exerted by the conduit wall on an external sensor, orother means for detecting pressure within the conduit 20.

The pump 44, which is depicted in the form a roller for purposes ofillustration and not limitation, is provided on the other conduit 22, onthe opposite side of the blockage 38 from the occluder 40 andpressure/force sensor 42. The pump also may be of any suitableconstruction or type of pump and may include, for example, a peristalticpump employing progressive compression of the conduit 22, such as byrollers, fingers or other structures to increase the pressure within theconduit. Illustrated in FIGS. 3-6 is a single roller 46 pump arrangementfor compressing the conduit 22 and increasing the internal pressure asdescribed in more detail below.

As shown in FIGS. 3-4, after the conduits 20 and 22 are connected andthe conduit 20 occluded, the pump roller 46 is pressed against conduit22, compressing and occluding the conduit. The roller is then movedtoward the connection site, where the blockage is located, asillustrated in FIG. 5, to increase the internal pressure within conduit22 between the occluding roller and the blockage 38. Of course, this isalso intended to be exemplary of any suitable pumping action and, forexample, a fixed peristaltic or other type of pump may not employ thesame depicted movement of roller 46 as shown in FIG. 5.

As the roller 46 approaches the connection site the internal pressure inconduit 22 between the roller and the blockage 38 (assuming it is acomplete blockage of the connection site) continues to increase and theconduit 22 continues to expand. Because of the blockage, however, thesensor 42 does not sense any pressure increase within or increase inforce due to expansion of the conduit 20. The internal pressure inconduit 22 increases until the blockage is broken, deformed or otherwisedisrupted (see FIG. 6) to provide an open passageway between theconduits

When the blockage 38 is disrupted and a flow path opened, the higherpressure within conduit 22 will now be transmitted through theconnection site into conduit 20, which has remained occluded by clamp orother occluder 40. The sensor 42 will detect the pressure increase inconduit 20 via expansion of conduit 20 or by other means, and thissensing may be used to trigger an indicator to the system and/or to theuser that the connection site has been opened.

At this point, the present system may optionally also test theconnection site for leakage, such as unconnected regions at theconnection site, pinholes or other apertures at the connection site.This feature can be used in combination with the above opening processor with other systems or fluid circuits or other connection formingapparatus employing a different connection technique or arrangement andnot requiring the above opening process. More specifically, referring toFIGS. 7a and 7b , after the blockage has been disrupted and theconnection site opened, the internal pressure is contained between theocclusion by the pump 44 in conduit 22 and the occluder 40 in conduit20. To sense connection integrity, the sensor 42 monitors the pressurefor a period of time, such as for a default period of up to about 30seconds, such as about 20-30 seconds, to allow detection of small leaks,although it could be a longer or shorter period as described earlier. Ifthe connection site is intact and has no leakage the sensed pressureshould be substantially constant over the period of time. This isillustrated in the graph of FIG. 7b , which is a graph showing pressuresensed vs. time and depicting what is to be expected in a condition ofconnection integrity with no leakage. On the other hand, with referenceto FIGS. 8a and 8b , if the connection site experiences leakage asdiagrammatically depicted as a hole or aperture 48 in FIG. 8a , thesensed pressure will decrease over the period of time. An exemplarygraph of such pressure decrease over a period of time is shown in FIG.8b . Of course, the slope of the decrease will depend on the size of theleakage. A large leakage may cause an abrupt pressure drop whereas asmall pinhole may be reflected in a much more gradual diminution insensed pressure. By detecting the pressure over a period of time, forexample up to about 30 seconds or thereabouts, the sensor is better ableto detect even small leakages.

Depending on the results of the integrity testing the sensor 42 canindicate directly or via a system controller whether the connection sitehas passed the pressure test, demonstrating that the connection isintact, or whether it has failed, and leakage is suspected. Thisindication can be visual, such as indicator light, audible, such as achime or tone, both or other. In addition, in the event leakage isdetected, the sensor may even be operable on its own or through acontroller, in addition to or separate from generating an alarmcondition, to actually prevent continued operation of any device orsystem with which the sensor is associated until the user addresses thesuspected leakage and clears the alarm condition.

Assuming that no suspected leak is detected, after the integrity checkis completed, the roller 46 is returned to its original non-occludingposition (as seen in FIG. 3) and the occlusion 40 is removed or opened,such as by releasing a clamp. The joined fluid conduits are now incondition to allow fluid flow between them, through the heat-bondedconnection with better assurance that the fluid will not be contaminateddue to an incomplete or non-intact connection.

FIGS. 10a and 10b shows one embodiment that serves to illustrate the useof the devices and methods described above as part of a larger fluidprocessing system. The system shown is for purposes of illustration andnot limitation to the features of the particular system shown.

More specifically, FIG. 10a depicts a blood processing system, generallyat 50, for post-collection processing blood collected from a donor. Thesystem includes a reusable, durable processing device 52, upon which adisposable, one-time use fluid flow circuit 54 may be mounted. Theillustrated durable device includes, as necessary, valves, pumps,sensors, hangers, scales, drive systems and the like for cooperatingwith the fluid flow circuit to control the flow of blood, bloodcomponents and other liquids through the system and carry out thedesired processing. The fluid flow circuit is made up of fluid flowtubing, containers and processing devices that may be assembled onto thedurable device and is, at least in part, preassembled andpre-sterilized, for conveying the blood and other associated fluidsthrough the processing without introducing extraneous materials orcontaminants. Only the disposable, one-time use fluid flow circuitcontacts the blood or other liquids, thus avoiding the need to sterilizethe durable hardware components and significantly reducingadministrative burdens and costs associated the processing.

As illustrated, the durable portion of the system may include, amongother things, flow control valves 56 a-c for assisting in controllingflow through flexible plastic tubing 58 of the fluid flow circuit 54.Typically, each valve includes a pair of clamping or pinching jaws,between which fluid flow tubing of the fluid flow circuit is placed whenthe flow circuit is assembled onto the face of the device 52. The valvesclose or open the tubing in response to commands from the operatingcontrol system of the device 52 based on the particular process selectedby the user. Typically the control system for device 52 employs aprogrammable microprocessor based controller that allows the device tobe configured for one or more of different selected procedures forprocessing blood. In the present description, it is shown forillustrative purposes only for processing a unit of whole bloodcollected from a donor, for example in a prior collection procedure. Thewhole blood may be processed, for example, to separate it intoconcentrated red cells, plasma and platelets, each of which findsapplication in particular medical situations, thus resulting in moreefficient usage of the collected blood.

The durable device 52 may also include pumps 60 a-c, such as peristaltictype pump, operable on the tubing 58 of the fluid flow circuit to directflow therethrough, a station 62 for receiving and interacting with ablood separation device, and various other sensors, weigh scales andother components to control fluid processing through the fluid flowcircuit.

In relation to the present subject matter, the durable device mayinclude heat-bonding connection site, generally at 64, that may includeapparatus such as but not limited to that described in U.S. publishapplication no. 2013/0153048, for forming a heat-bonded connection, suchas a sterile connection, between tubing (conduit) portions of the fluidcircuit. In the illustrated embodiment, the connection formed is betweena flexible thermoplastic (PVC) tubing segment 66 of the preassembleddisposable fluid circuit 54 and flexible thermoplastic (PVC) flow tubingsegment 68 attached to a container or bag 70 of collected blood.

The heat bonding connection device site 64 is diagrammatically shown inFIG. 10b , except for the actual connection forming apparatus,specifically FIG. 10b depicts the two tubing segments 66 and 68 at thesite prior to formation of the heat bonded connection. This site 64 ofthe device also may include a pressure/force sensor 72 for sensingpressure in the blood bag tubing segment 68, as will be described morefully later.

Turning now to the disposable fluid flow circuit 54 in the illustratedin FIG. 10a example, the preassembled circuit includes a bloodseparation device 74, containers or bags 76 (e.g., containing RBCadditive solution), 78 (e.g., for receiving concentrated RBCs) and 80(e.g., for receiving plasma), leukoreduction filter 82 and associatedflexible tubing 58 connecting the various components in a fluid flowrelationship. The preassembled circuit may be pre-sterilized, and thetubing extension or segment 66 to be joined to the blood bag mayterminate at a heat sealed end to preserve sterility.

When mounted on the separation device, the components of thepreassembled flow circuit are placed on or in their selected locations,the blood separation device 74 in the station 62, the tubing in thevalves 56, sensors, and pumps 60 and the bags 76-80 on the varioushangers.

To carry out the illustrated blood processing, the bag of collectedblood 70 is suspended from the appropriate hook or hanger and tubingsegment 68 is placed in valve 56 a, and in association with thepressure/force sensor 72. Together with tubing segment 66 of thepreassembled fluid circuit, tubing segment 68 are placed in operativeposition on the connection forming apparatus. This is the position showndiagrammatically in FIG. 10 b.

Referring to FIGS. 11-12, FIG. 11 diagrammatically shows the tubingsegments 66, 68 after the connection is formed by the connectionapparatus, and a thermoplastic portion or skin 82 is formed during theconnection process and blocks flow through the tubing segments. In amanner similar to that described earlier, the pump 60 a occludes thefluid circuit tubing 58, which extends from tubing segment 66, and valve56 a clamps the tubing segment 68 closed. Valve 56 b is upstream of thejunction between tubing segment 66 and the remainder of the fluid flowcircuit and also closes the tubing at that location.

Within a relatively short time after the heat-bonded connection isformed, the pump 60 a is activated and increases the pressure in thetubing segment 66 as seen in FIG. 11, until the thermoplastic blockingportion 82 is disrupted and opened to flow, as illustrated in FIG. 13.

Optionally, the pressure/force sensor 72 monitors the pressure in thetubing segment 68 to evaluate the integrity of the connection, asdescribed earlier. If the connection between the tubing segments 66, 68is intact and without leaks, the pressure/force vs time relationshipsensed by the sensor will be substantially as shown in FIG. 14b , andthe device control system may so indicate to the user, who may proceedwith the blood processing. If, on the other hand, the connection site isnot intact and experiencing leakage, the pressure/force vs timerelationship will be similar to that shown in FIG. 15b , and the devicecontrol system may generate an audio or visual alarm to the user and/ormay prevent continuation of the process until the user intervenes.

In conclusion, although the present subject matter has been describedwith reference to specific devices and methods, that is for the purposeof description and not limitation. It is contemplated, for example, thatthis subject matter may be used with other devices, systems and methods,and reference should be made to the attached claims for an understandingof the scope of certain aspects of the present subject matter.

The invention claimed is:
 1. A method for opening a heat-bondedconnection formed between two hollow, flexible, thermoplastic conduits,which connection includes a frangible portion of thermoplastic materialformed during the heat bonding and at least partially blocking internalcommunication between the conduits, the method including: creating apressure difference between the inside of at least one of the conduitsand the ambient atmosphere sufficient to cause expansion of a wall ofthe tubing conduit in the vicinity of the frangible portion ofthermoplastic material to disrupt the frangible portion and reduce theblocking.
 2. The method of claim 1 in which the pressure difference iscreated before the thermoplastic material at the connection has fullyhardened from the heat-bonded connection.
 3. The method of claim 1 inwhich the pressure difference is created when the thermoplastic materialhas a temperature above its glass transition temperature.
 4. The methodof claim 1 in which the pressure difference is created within about 10seconds of the formation of the heat-bond connection.
 5. The method ofclaim 1 in which the pressure difference is created by increasingpressure inside of the tubular conduit above ambient pressure.
 6. Themethod of claim 1 including occluding one of the thermoplastic conduitsand increasing the pressure in the other of the thermoplastic conduitsuntil the frangible portion is disrupted.
 7. The method of claim 6including sensing the pressure in one of the conduits after thefrangible portion is disrupted to determine the integrity of theheat-bond.
 8. The method of claim 7 including sensing the pressure overa time period.
 9. The method of claim 7 in which the pressure is sensedfrom an initiation of the step of increasing pressure in the other ofthe conduits.
 10. The method of claim 6 including sensing the pressurein the one of the conduits to determine disruption of the frangibleportion.
 11. The method of claim 6 including increasing the pressure inthe other of the conduits until a pressure increase is sensed in the oneof the conduits.
 12. The method of claim 11 in which the pressureincrease does not exceed a burst pressure of the other conduit.
 13. Amethod of forming and opening a heat bonded connection between twothermoplastic tubes comprising: heating one end of each tube until it isin semi-molten state and bringing the ends into direct contact to form aheat bonded connection therebetween which includes a frangible portionof the thermoplastic tube material at partially blocking internal fluidflow communication between the tubes; increasing pressure within one ofthe tubes when the thermoplastic material at the connection site isabove the glass transitional temperature of such thermoplastic materialwhile occluding the other of the tubes at an occlusion location; sensingthe pressure in the other of the tubes between the connection site andocclusion location while the pressure is increased in the one tube;increasing the pressure within the one tube until a pressure increase issensed in the other tube indicative of disruption of the frangibleportion; continuing to sense the pressure in the other tube for a periodof time after the disruption to determine the integrity of the heatbonded connection; and generating an audible or visual alarm in theevent the continued sensing of pressure in the other tube indicatesleakage at the connection site.
 14. The method of claim 13 includingsensing the pressure in the other tube for up to about 30 seconds afterdisruption.
 15. The method of claim 13 wherein the pressure is increasedin the one tube within less than about 10 seconds after the connectionis formed.
 16. The method of claim 13 wherein the pressure in the onetube is increased to about 19-29 psi.
 17. The method of claim 13 whereinthe tubes are made of polyvinylchloride.
 18. The method of claim 17wherein the tubes have an internal lumen diameter of about 0.118-0.126inches (3.0 mm -3.2 mm) and a wall thickness of about 0.025-0.03 inches(0.63 mm -0.76 mm).
 19. The method of claim 18 wherein the pressure isincreased in the one tube within less than about 10 seconds afterconnection is formed and the pressure in the other tube is sensed for atime period of up to about 30 seconds after disruption; and theocclusion opened if no leak is detected within the time period.